Evaluation of the optimal plate position for the fixation of supraglenoid tubercle fractures in warmbloods.

OBJECTIVES

To determine scapular cortex thickness, distal scapular bone density and describe the exact suprascapular nerve course to evaluate the best plate position for the fixation of supraglenoid tubercle fractures in horses.

METHODS

Twelve equine cadaveric shoulders were examined with computed tomography. Computed tomography morphometry and density measurements (Hounsfield units [HU]) of the scapula were recorded. Statistical comparisons were made between the cranial and caudal aspects of the scapula. Dissection of each shoulder was performed and the suprascapular nerve course was described morphometrically and morphologically.

RESULTS

The suprascapular nerve was found on the periosteum and embedded in connective tissue at the cranial aspect of the scapula. It ramified proximally and distally into the supraspinatus muscle, coursed caudolaterally at a median of 2 cm (1-2 cm) distal to the scapular spine and ramified proximally and distally into the infraspinatus muscle. The scapular cortex measurements (HU) cranially were significantly larger than caudally at most levels of the scapula. The bone density of the distal scapula cranially (651.3 ± 104.2) was significantly lower than caudally (745.7 ± 179.1).

CLINICAL SIGNIFICANCE

For surgical access to the supraglenoid tubercle, knowledge of the anatomy is important. It is easiest to avoid the suprascapular nerve at the most cranial aspect of the scapula, where it has not yet ramified. For a stable fixation, knowledge of the characteristics of the equine scapula, such as scapular cortex thickness, is important.